Signal intelligence is an integral part of intelligence collection for law enforcement and national security. To effectively intercept transmitted communications signals and find the locations of the transmission, direction finding (“DF”) antennas are positioned in strategically selected locations. The criteria for selecting locations for the DF antennas include the range of the signal source, the size and sensitivity of the antenna, and other tactical concerns.
Antennas that are sensitive to the electric field of electromagnetic signals (referred to as “E-field antennas”) are commonly used to intercept communications because of their relatively small size and relatively high sensitivity. However, the effectiveness of E-field antennas may be reduced significantly depending on certain external factors. For example, E-field antennas generally need to be positioned on a level ground plane and away from significant man-made structures, natural terrain features, and power emission sources. Additionally, although E-field antennas are relatively small, their physical size may render concealment of the antennas problematic in certain environments. Because of these concerns, E-field antennas may limit the range of tactical options available to a tactician, which adversely affects law enforcement and national security.